We prepared the inverted polymer solar cells (PSCs) with a fluorine-doped tin oxide (FTO) as a transparent electrode and with TiO2, WO3 and WOx as selective charge transport layers. An adequately thick TiO2 nanoparticles layer was employed for covering a very rough FTO surface. Using a solution-based WOx film instead of a vacuum deposited WO3 layer in inverted polymer solar cells showed comparable device performance. A self-assembled molecular (SAM) layer of PCBA and N719 on top of TiO2 improves the device performance by reducing the series resistance at the interface between the active layer and the TiO2 film. The power conversion efficiency (PCE) was improved by 16%, especially in the case of [6,6]-phenyl-C-61-butyric acid (PCBA). (c) 2010 Elsevier B.V. All rights reserved.